Method and apparatus for oil purification



July 20, 1943. E. H. CARRUTHERS 2,324,763

- METHOD AND APPARATUS FOR OIL PURIFICATION Filed April 17, 1940 R 156mm)? gggrs BY Q 4 ya -%Z;S- ATTORNEY.

- .paratus for purifying the lubricating oil llatente d Jul! [UN T I Ma'rnon sT 'rss PATENT ole-rice AND mans-ms son on.

roarr'rca'rron seen Hunter car-rather, Seneca Falls, n.1,-

assignmen signor, by mesne into The Sharples grgoration, Philadelphia, Pm, a corporation of ware Application Aprill'l, 1m, Serial no. 330,146 w 1 Claims. (01. 210-62 J of the oil and My invention relates to liquid purification'systerns and;more,particularly, to a method and apf a prime mover.. While the method and apparatus or my invention will be described in connection with the purification of the lubricating oil of an internalcombustion engine, it will be understood that the invention has broader application. For example, the system might beused in connection 'with the purification of the lubricating oil-of turblues, and other prime movers and in connection with the purification of. transformer oils.

In the lubricating oil purification systems now employed in connection with Diesel engines, particularly those of large horse power, it has been I customary in the past to use either of two methods: either'the'oil was centrifuged to re move impurities; or-the oil was passed through a filter. A centrifuge has distinct advantages in connection with the purification of internal cornbustion engine lubricating oil. Amongthese may be-mentioned the facts that the centrifuge will 'keep the oil mechanically clean and remove insol- 1 uble impurities, including water, carbon,- and other impurities. Moreover, a centrifuge is a relatively high capacity machine and is capable of handling the lubricating oil of theengine sum! ciently rapidly as to turn over the complete oiling system in a,few hours. Moreover, a centrifuge operates efficiently at relatively low oil temperatures, is inexpensive to operate, and easy be centrifuged, reduce the acidity of the oil and appear, to someextent, to bring the oil to the condition where it acts as a solvent and helps to keep the working parts of the engine bright and clean.

Filtering systems, on the other hand, employing, for example, fullers earth, or special clays. are rather expensive .to operate, because of the constant supervision and maintenance required. Moreover, where special clays are employed, the

cost of the clay, and the rapidity with which it loses its efiiciency as a filtering medium, requiring frequent renewal of the clay, adds materially to the cost of operating a filtering system. In

addition, filtering systems are capable only of small capacities so that unless an abnormally large filtering system is employed with prohibitive costs, they'are as a rule unable to keep up with the contamination produced during normal eng'ine operation.

A decided disadvantage in filtering with fuller's earth, clays, or other filtering media, lies in the fact that the oil must pass through the impuri ties which have already been filtered out of the oil; With the filter doing all the work of removing impurities, the fullers earth or clays, are soon clogged with impurities and rendered inactive. Fuller's earth, while oneof the best filtering media, has the distinct disadvantage that a small 7 percentage of moisture in the claywill render its original somewhat golden color'and the oil after being centrifuged retains the black color characteristic of used oil. 4 i For the reason that centrifuging will not restore used oil to its original color and will not re-' tion of the operators'of Diesel engines prefer to employ filtering systems, notwithstanding the high maintenance costs of filtering systems. F11- move resins, gums, light colloidal carbon and certain other impurities, a substantial proporthe clay inactive. More than that, is the ever present danger that through accident or care.-

lessness, some of the. filtering medium may pa s through to the engine system with the possibility of causing considerable damage thereto.

An objectv of my invention is to provide an oil purifying system for a prime mover in which a centrifuge and a filter are combined so as to provide a more efficient oil purifying system and i a system which is inexpensive to operate and easy to maintain.

Another object of my invention is to provide an oil purification system wherein a centrifuge and a filter are combined, connected together,

and operated so as to combine the advantages of a centrifuge and a filter and eliminate most of. the disadvantages of each.

My invention further contemplates a novel apparatus and method of purifying particularly lubricating oils. 3 Other objects andadvantages of my invention will be particularly pointed out in the claims and tering systems, in addition to restoring the color will be apparent'from the following description,

removing impurities which cannot ities.

when taken in connection with the accompanying drawing, in which, the figure is a diagrammatic bustion engine is represented by the numeral l, I

or the numeral I may represent the place of collection of liquid to be purified other than the sump of an internal combustion engine, as, for

example, the place of collection of oil for lubrication of a steam turbine. A pump 2, which may be of any suitable type, has its suction connected by conduits or pipes 3 and 4 to the sump l. Interposed inthe conduit 3 is a flow sight 6, a valve 1 'l, anda vacuum or pressure gauge 8. By regulating the valve I the quantityof oil withdrawn from the sump for purification may be regulated as desired. J

From the pump 2 the oil to be purified is forced through a heater 9. The heater may be of any conventional construction such, for example,as a coil type heater adapted to heat the oil, by suitable regulation of the heater, to any desired temperature. While, when desired, heating of the oil may be dispensed with, a centrifuge operates considerably more efficiently when the temperature of the oil is raised to approximately 180 F. or 200 F.

The pressure of the pump 2 serves to force the oil through the heater and to the intake of a centrifuge, diagrammatically illustrated at ii. The centrifuge may be of any desired type and may comprise a rotatable bowl adapted to be rotated at high velocities so as to cause a separation of the various components of the contaminated oil in accordance with their specific grav- The heavy ingredients, such as water and a large proportion of carbon particles and other impurities, are removed from the contaminated oil and from the system by the centrifuge, as is well known in the art to which this invention applies.

From the discharge of the centrifuge, the centrifuged oil is picked up by the suction of a pump 12 and forced through a pipe or conduit l3 and a pipe or conduit it to the intake side of a filter, diagrammatically illustrated at E6. Interposed between the pump i2 and the filter are a valve ii and a pressure gauge it. The connections between the pump and the filter may be vented to atmosphere, as indicated at I9, or the connection It may be employed to connect the system to a source of air pressure for draining the filter.

The filter employed in the system may be of any suitable construction and the filtering material may be any suitable filtering medium, such as fullers earth, or. other special clay filtering medium. The pressure of the pump l2 serves to force theoil through the filter aided, to a certain extent, by the vacuum produced by the pump 2, the discharge side of the filter being connected through a conduit 2| to the suction of the pump 2. A flow sight 22 and a valve 23 may be interposed in the line 2 i.

The conditioned and purified oil is returned to the sump through a; conduit 24 in which a flow sight 26 may be located. The conduit 2 connects with the conduit l 3, as indicated at 21. The flow through the conduit 26 from the purification system is controlled by a valve 28. The valve 2% may be of any suitable type, but I prefer to em ploy an automatic pressure type valve which is pressed toward a closed position by means of a possible to leave the valve 28 in a set position and regulate the return flow of oil to the filter by adjusting the valve l1. Moreover, if desired, the quantity of oil returned to the ,sump may be regulated by adjusting both the valve i1 and the valve 28. v

One of the important features of my invention is the fact that all of the oil passing through the filter flows to and through the centrifuge. The vacuum created in the conduits 2i, 4 and 3 by the pump 2, causes a fiow of oil through the conduit 4 and into the intake of the pump both from the sump and from the filter so that there can be no flow of oil from the conduit 2| to the sump. Thus it is impossible for clay migratin from the filter to reach the sump of the engine through the conduit 3. A centrifuge will readily separate out fuller's earth or other filtering media commonly employed in filters. Since all of the filtered oil must pass through the centrifuge, the oil flowing through the conduit 24 back to the sump can contain no clay, even should clay migration occur.

The fact that in my system the engine is protected should clay migration occur, enable the filter itself to be built with less positive means to prevent clay migration. In the conventional filter system, the positive protection necessary to prevent, insofar as possible, any possibility of the clays flowing with the oil to the'sump of the engine must be built into the filter itself with a resultant relatively high resistance to flow through the filter. Moreover, such high resistance to flow through the filter necessitates higher pump pressures on the filter. In the present system a filter may be employed having much higher flow rates and much quicker starting time than would be possible if, in the filter itself, complete and before it has been removed from the filter.

Since the clays of veven a. medium sized filter will retain about ten to twelve gallons of oil, the fact that it is possible to recover this oil, with little trouble or expense, is a decided advantage. The draining of the filter, when the clay is to be replaced, is accomplished by closing the valve ll, opening the vent valve I9 and closing valve 1 or leaving this valve only partly open. The suction pump 2 will then draw'a vacuum on the discharge side of the filter which will draw out a .large proportion of the oil retained by the filtering claysa'nd which in most systems is thrown away with the spent filtering medium. If desired, the draining of the filter may be expedited by applying air pressure at the vent I9.

In the operation of my system the oil is drawn passed through the heater to the centrifuge by the pumpi. The oil drawn into the pump contains a certain proportionof oil which hasalready passed through 'thefilter. After discharge from the centrifuge the oil is picked up-bythe'pump l2 and returned to the filter, a certain regulated proportion of this conditioned oil by-passing' the filter and fiowing through the valve 28 and the conduit 24 to thesump I. Q

In starting the system, when the engine crank case is filled with dirty oil, it'is desirable to cut .the filter out and merely centrifuge the oil for a period of time so as to remove most of the im purities before the filter is put into operation.

This may be accomplished by closing the valves I! and 23'. As soon as the major portion of the impurities have been removed, the valves I1 and 23 may be opened so as to pass a certain proportion of the oil discharged from the centrifuge through the filter. A good arrangement is to adjust the valve 28' (or the valve l1) so that about half of the oil discharged from the centrifuge is returned to the sump. With the valve 28 thus adjusted, the oil returning to the sump may not be thoroughly clean (assuming the system is started with the sump full of dirty oil), but as the operation is continued the oil flowing to the sump will become more and more clean. Assuming the centrifuge and filter have sufflcient capacity to turn over all the oil in the lubri-' cation system at frequent intervals and to remove impurities faster than they are formed, a

condition will be arrived at where the oil retuming to the sump is substantially free of impurities.

The centrifuge of the system not only removes dirt, carbon, water, and other insoluble impurities, but also protects the engine against clay migration. Moreover, the centrifuge removes most of the impurities from the contaminated oil before the oil is passed through the filter. This leaves the filter with but little work to do, tending greatly to increase the active life of the filtering material. The filter, as mentioned above, removes impurities, such as resins, gums and fi-ne carbon particles, which cannot be removed from the oil by means of a centrifuge. Moreover, the oil coming from the filter. to a certain extent,

conditions the oil coming from the engine sump so that the impurities may be centrifuged more readily.

The combination of a centrifuge and a filter requires only infrequent cleaning of the centrifuge bowl and only infrequent replacement of the fuller's earth or other filtering medium. Due

to the rapid flow which may be maintained appreciated that the apparatus and method disclosed have other applications. It will further be appreciated that various changes may be made, particularly in the form and relation of invention, as set forth in the appended claims.

I claim:

1. In a purification system having a source of contaminated liquid, in combination, centrifugal separator means, a filter, means for liquid from said source to said centrifugal separator means, means for passinga part of said-liquid from said centrifugal separator means through said filter,means for passing the filtered liquid 3 back to said source, and means for-passing another part of said liquid from said centrifugal separator means back 'to said source without passing it through said filter, said means for passing said filtered liquid back to .said source including centrifugal separator means through which said liquid is adapted to be passed in fio ing from said filter to said source.

2. In a purification system having a source of contaminated liquid, in combination, centrifugal,

separator means, a filter provided with a filter clay, means for passing liquid from said source to said centrifugal separator means, means for passing a part of said liquid from said centrifugal separator means through said filter clay, means for passing the filtered liquid back to said source, and means for passing another part of said liquid from said centrifugal separator means back to said source without passing it through said filter, said means for passing said filtered liquid back to said source including centrifugal separator means through which said liquid is adapted to be passed in flowing from said filter to said source.

3. In a purification system having a source of contaminated liquid, in combination, a centrifugal separator, a filter, means for directing liquid fronrsaid source to said centrifugal separator, means for passing a part of said liquid from said centrifugal separator through said filter,-

means for passing the filtered liquid back to said source, and means for passing another part of said liquid from said centrifugal separator back to said source without passing it through said filter, saidv means for passing the filtered liquid back to said source including a pump interconnected with said means for directing said liquid from said source to said centrifugal separator,

whereby liquid returning from said filter to said source is passed. through said centrifugal separator to eifect removal therefrom of impurities derived from the filter.

4. In a purification system having a source of contaminated liquid, in combination, a centrifugal separator, a filter, means for passing liquid from said source to said centrifugal separator, means for passing a part of said liquid from said centrifugal separator through said filter, means liquid from-said centrifugal separator to said source.

v parts, without departing from the spirit of my 5. In a purification system having a source of contaminated liquid, in combination, a filter provided with a filter clay, a centrifugal separator, means at a point in the line of fiow of liquid after it has left said filter for forcing the liquid which has passed through said filter clay through the centrifugal separator before the liquid is returned to the point of use, and a vent in said system arranged at a point in the line of flow of liquid in advance of said filter, a valve controlling said vent, whereby said means for forcold which comprises passing said liquid from the source of contaminated liquid through a centrifugal trifugal separator, removing liquid from the zone of centrifugation, filtering a portion of the centrifugally purified liquid, returning said filtered separator, subjecting said contaminated liquid to centriiugation in said cen-- liquid to said source and again subjecting it to centrifugal purification and thereby removing solid impurities while said liquid is being returned from the filtering operation to said source, and passing another part of the initially centrifugally purified liquid to said source without subjecting this last-mentioned part to filtration.

7. A process as defined in claim 6, in which the liquid passing from said filtering step to said source is subjected to centrifugation along with contaminated liquid freshly removed from said source, during passage of said filtered liquid from said filtering operation to said source.

EBEN HUNTER CARRUTHERS. 

